1. Field of the Invention
The present invention relates to an apparatus and method for assembling a flat harness in which juxtaposed electric wires are covered with a sheet.
2. Description of the Related Art
A method for producing a flat harness in which a plurality of electric wires are laterally arranged in a flat form and integrated with one another is disclosed in Japanese Patent Public Disclosure No. HEI 9-29015. In this method, a plurality of electric wires are arranged in a flat plane to form a harness, and are disposed on a central portion of a flexible sheet having a hot melt adhesive on a surface thereof. Opposite side ends of the sheet, which extend beyond opposite side ends of the flat harness, are folded over onto the harness. Distal parts of the opposite side ends of the sheet are overlapped on the harness. In this condition, the harness and sheet are clamped between upper and lower dies of a heating press machine, and are heated and pressed to be joined together.
In this manner, a plurality of electric wires are arranged in a flat form and covered with a sheet, on which a hot melt adhesive is applied, to produce a flat harness. Such a flat harness is suitable for containment in a narrow space, such as the space between a roof panel and a molded ceiling in a vehicle, such as an automobile. However, an apparatus for producing such a flat harness can be large and involve complex processes.
For example, in order to envelope the harness having a plurality of electric wires together with a sheet provided with hot melt adhesive on a surface, it is necessary to incorporate a heating device in a molding press in order to soften the hot melt adhesive. This necessarily involves the provision of a large scale production apparatus. In order to carry out a suitable heat pressing process in a molding press, the following steps are required. The opposite side ends of the sheet must be folded to make creases on the sheet, and then unfolded or returned to their original position. Next, the sheet must be enveloped around the harnss wires to temporarily hold them, prior to heating and pressing.
A sheet provided with a pressure sensitive adhesive on a surface of the sheet may be used instead of a sheet on which hot melt adhesive is applied. However, a worker will often touch the pressure sensitive adhesive inadvertently, which will interfere with the assembly and covering process. Furthermore, it is difficult to properly cover the harness wires with the she(t in a compact manner while tightly attaching the sheet to the opposite side ends of the juxtaposed harness wires.
The present invention has been made in view of the above described situation. Accordingly, an object of the present invention is to provide apparatus and method for easily and properly producing a flat harness by covering juxtaposed electric wires with a sheet having a pressure sensitive adhesive on a surface thereof.
According to one aspect of the present invention, there is provided an apparatus for assembling a flat harness in which a plurality of juxtaposed electric wires are covered by a sheet having a pressure sensitive adhesive layer on a first surface thereof. The apparatus includes a covering device for assembling the sheet around the plurality of juxtaposed wires. The covering device includes a central plate on which a central portion of the sheet is supported, a first side plate connected through a first hinge portion to a first side edge of the central plate in a foldable manner for supporting a first lateral portion of the sheet, and a second side plate connected through a second hinge portion to a second side edge of the central plate in a foldable manner for supporting a second lateral portion of the sheet. The covering device also includes an engagement device for holding the sheet supported on the ceniral plate the first side plate, and the second side plate.
According to a further aspect of the present invention, the engagement device includes an engagement plate having a surface which is configured to contact the first surface of the sheet. The engagement plate may be connected through a third hinge portion to a side edge of the second side plate in a foldable manner. The surface of the engagement plate may include a release agent layer provided thereon.
According to a further aspect of the present invention, the engagement device includes a suction source for applying a negative pressure to a second surface of the sheet. Further, the central plate may include a porous plate provided on an upper surface thereof, and the suction source may apply the negative pressure to the second surface of the sheet through the porous plate.
According to a further aspect of the present invention, the covering device may further include a sheet positioner for aligning the sheet in a predetermined position on the central plate, the first side plate and the second side plate. The sheet positioner may include a sheet end positioning portion for aligning an end of the sheet. The sheet end positioning portion may be provided on the second side plate. The sheet positioner may include sheet lateral edge positioning portions for aligning lateral edges of the sheet. The sheet lateral edge positioning portions may be provided on the central plate, the first side plate and the second side plate.
According to a further aspect of the present invention, at least one clamp member for holding a portion of the plurality of juxtaposed electric wires may be provided. Further, two clamp members may be provided for holding opposite end portions of the plurality of juxtaposed electric wires.
According to a further aspect of the present invention, a support member for supporting the covering device in a position between the two clamp members may be provided. The support member may be movable between a first position in which the covering device is spaced away from the plurality of juxtaposed electric wires and a second position in which the covering device is adjacent to the plurality of juxtaposed electric wires.
According to another aspect of the present invention, a method for assembling a flat harness is provided which includes holding a plurality of juxtaposed electric wires with at least one clamping member, providing a central plate and first and second side plates which are connected in a foldable manner to first and second side edges of the central plate through first and second hinge portions, and providing a sheet having a pressure sensitive adhesive layer on a first surface thereof, wherein the sheet has a central portion, a first lateral portion and a second lateral portion. The method includes mounting the sheet on the central plate, the first side plate and the second side plate, and pressing an engagement plate having a release agent layer onto the second lateral portion of the sheet to hold the second lateral portion of the sheet against the second side plate.
The method further includes disposing the plurality of juxtaposed electric wires on the central portion of the sheet, folding the first side plate onto the central plate such that the first lateral portion of the sheet is folded over and fixed on the plurality of juxtaposed electric wires, releasing the engagement plate from the second lateral portion of the sheet, and folding the second side plate onto the central mounting plate such that the second lateral portion of the sheet is folded over and fixed on the plurality of juxtaposed electric wires.
The method may further include aligning the sheet on the central plate, the first side plate and the second side plate with a sheet positioner.